THE EFFECTIVENESS OF TA PREPARED BY ION-ASSISTED DEPOSITION AS A DIFFUSION BARRIER BETWEEN COPPER AND SILICON

The diffusion barrier properties of Ta, both as deposited without ion bombardment and deposited concurrent with ion energy, were investigate d in the Cu/Ta/Si contact system using Auger electron spectroscopy, x- ray diffraction, optical microcopy, transmission electron microscopy: and sheet resistance measurements. It was found that the ion bombardme nt during deposition of Ta films influenced the microstructural charac teristics, such as the packing density of grain boundaries, the grain size, and the preferred orientation of Ta grains. The Ta film deposite d concurrent with 150 eV ion energy (0.13 mA/cm(2)) showed the increas ed packing density of grain boundaries, low resistivity, and preferred orientation. The densification of grain boundaries of the Ta barrier layer, followed by an increase of silicide formation temperature, sign ificantly enhanced the barrier property of Ta in the Cu/Ta/Si system.